化简求值
3(-2x+1)-5(2-x) 其中X=-5
1-3(m-n)-{m-[2n(m-n)]}. 其中M=-1 N=3分之2
(2x-3y-2)-(x-4y+1) 其中X+Y=3
化简
x-2x+1 7a+3b-8-5a+2b -3a+b-(b-2a) 3x-[5x-(二分之一-3)]
化简求值
3(-2x+1)-5(2-x) 其中X=-5
1-3(m-n)-{m-[2n(m-n)]}. 其中M=-1 N=3分之2
(2x-3y-2)-(x-4y+1) 其中X+Y=3
化简
x-2x+1 7a+3b-8-5a+2b -3a+b-(b-2a) 3x-[5x-(二分之一-3)]
(1)当X=-5时,
3(-2x+1)-5(2-x)
=-6x+3-10+5x
=-x-7
=5-7
=-2
(2)当M=-1 N=3分之2时,
1-3(m-n)-{m-[2n(m-n)]}.
=1-3(m-n)-{m-[2mn-2n^] } (注:n^表示的是2Xn的平方)
=1-3(m-n)-{m-2mn+2n^}
=1-3m+3n-m+ 2mn-2n^
=1-4m+3n + 2mn-2n^
=1-4X(-1)+3X 3分之2+2X(-1)X3分之2-2X(3分之2)平方
=1+4+2-3分之4-9分之8
=4又9分之7
(3)当X+Y=3时,
(2x-3y-2)-(x-4y+1)
=2x-3y-2-x+4y-1
=x+y-3
=3-3
=0
(4)
x-2x+1 7a+3b-8-5a+2b -3a+b-(b-2a) 3x-[5x-(二分之一-3)]
=x-2x+1 7a+3b-8-5a+2b -3a+b-b+2a) ?3x-5x+二分之一-3
=-x+12a+5b........?
1, 3(-2X+1)-5(2-X)=-6X+3-10+5X=-X-7
把X=-5带入得 5-7=-2
2. 1-3(M-N)-{M-[2N(M-N)]}=1-3M+3N-M+2MN+2N*N=1-4M+3N+2MN-2N*N
把M=-1,N=2/3带入得 1+4+2-4/3-8/9=7-12/9-8/9=7-20/9=43/9
3. (2X-3Y-2)-(X-4Y+1)=2X-3Y-2-X+4Y-1=X+Y-3
把X+Y=3带入得3-3=0
4。 X^-2X+1=(x-1)^
5. 7a+3b-8-5a+2b-3a+b-(b-2a)=-a+6b-8-b+2a=a+5b-8
6. 3x-[5x-(1/2-3)]=3x-5x+5/2=5/2-2x
3(-2x+1)-5(2-x) =-6x+3-10+5x=-x-7
X=-5,
-x-7=5-7=-2
1-3(m-n)-{m-[2n(m-n)]}. 其中M=-1 N=3分之2
=1-3m+3n-{m-2mn+2n^2}
=1-3m+3n-m+2mn-2n^2
=1-4m+3n+2mn-2n^2
=1+4+2-4/3-8/9
=7-20/9
=43/9
(2x-3y-2)-(x-4y+1) 其中X+Y=3
=2x-3y-2-x+4y-1
=x+y-3
=3-3
=0